Injection devices for internal combustion engines are believed to be generally understood. From the printed publication DE 10 2009 000 894 A1, for example, a fuel-supply system is discussed, which supplies mixed fuel containing alcohol and gasoline to a plurality of cylinders of an internal combustion engine. The mixed fuel includes what is called a main fuel and a supplementary fuel, the supplementary fuel having a lower alcohol concentration than the main fuel. The supplementary fuel is injected in the direction of a first and second intake valve of each cylinder by two separate first fuel injectors or by a single second fuel injector. The main fuel is injected in the direction of a first and second intake valve of each cylinder, via the two separate first fuel injectors. The two fuel injectors are therefore used alternatively for the injection of main fuel or supplementary fuel.